(a) Field of the Invention
The present invention relates to a system for activating a fuel cell stack, and more particularly, to an activation apparatus of a fuel cell stack which enables an activating process of the fuel cell stack and a performance evaluation to be unmanned and automated.
(b) Description of the Related Art
Generally, a fuel cell includes an electrode that provokes an electrochemical reaction between fuel and oxidizing agent, a polymer electrolyte membrane that transfers protons generated by the reaction, and a separator that supports the electrode and the polymer electrolyte membrane. Currently, the polymer electrolyte fuel cell is commonly being used as the fuel cell for vehicles. The polymer electrolyte fuel cell has the advantage of not corroded and regulation of electrolyte is not required, since it has higher efficiency than other forms of fuel cells, the current density and the output density are high, it uses a polymer electrolyte, and the startup time is substantially reduced.
In addition, since the polymer electrolyte fuel cell is an environmentally friendly power source that produces no exhaust emissions except pure water research is being conducted in the field. Such an electrolyte fuel cell may generate electrical energy while generating water and heat through the electrochemical reaction between a fuel including hydrogen and an oxidizing agent such as air.
In other words, in the electrolyte fuel cell, supplied fuel is divided into hydrogen ions and electrons in the catalyst of the anode electrode, and the divided hydrogen ions cross over to the cathode through the polymer electrolyte membrane to generate electrical energy and produce water from the combination of the supplied oxidizing agent and electrons are injected along external wires. In an actual fuel cell for vehicles, individual unit cells are stacked to obtain required potential, and the stacked structure of unit cells is referred to as a stack.
Meanwhile, an electrode of the fuel cell is formed by mixing a hydrogen ion carrier and a catalyst, and the activity of the electrochemical reaction may be decreased in initial operation after the fuel cell is manufactured since a transfer port is blocked and the carrier may not reach the catalyst, the carrier of hydrogen ions forming a triple phase interface is not easily hydrolyzed in the initial operations, and continuous mobility of the hydrogen ions and electrons is difficult secure. Accordingly, to maximally secure the performance of fuel cells after assembling the membrane-electrode assembly including the electrode and the polymer electrolyte file, and the stack which is an assembly of fuel cells for generating electricity including separators, a process of activation and performance evaluation of the fuel cell stack is performed.
The object of the activation and the performance evaluation is to remove inflow of residual impurities during the process of manufacturing the membrane-electrode assembly and the stack, to activate the sites which do not participate in the reaction, and to secure passages for hydrogen ions by sufficiently hydrolyzing the electrolyte included in the polymer electrolyte membrane and the electrode as well as to secure the passage through which reactants move to the catalyst. Although such an activation of the fuel cell stack has been performed in various methods in the related art, a main method of activation is to detect the voltage of the fuel cell of the stack while operating the stack for a substantial amount of time under a predefined voltage.
For this, equipment for activating the fuel cell stack based on the related art may perform the processes for activating the fuel cell stack and evaluating the performance by supplying the fuel and the oxidizing agent into the fuel cells after manufacturing a stack in which a plurality fuel cells are layered, and by monitoring the voltage of the fuel cells while applying electrical energy generated from the fuel cells to an electric load apparatus. In such processes of activating the fuel cell stack and evaluating the performance, connectors of the voltage measuring equipment are connected to a terminal that protrudes from each fuel cell of the stack, an output cable connected to the electric load apparatus is connected to output terminals at both sides of the stack, and a fluid supplying tube for supplying fluids (e.g., hydrogen, air, and cooling water) is connected to a manifold of the stack.
In the process of connecting the connectors of the voltage measurement equipment to the terminals that protrude from each fuel cell of the stack, the connectors and the terminals of each fuel cell are manually connected. Accordingly, in the related art, since the connectors of the voltage measuring equipment are manually connected to the terminals of the stack, workability may be deteriorated, an excessively substantial period of time is required for the overall process for connecting the connectors and the terminals, and stack damage may occur during the work of connecting the terminal.
In addition, in the process of connecting the output cables connected to the electric load apparatus to the output terminals at both sides of the stack, a worker clamps a bus bar connected to the electric load apparatus and the output cable to the output terminal of both sides of the stack with a bolt. Accordingly, in the related art, the worker may be exposed to a danger of electric shock when manually connecting and detaching the output cable to/from the output terminal on both sides of the stack. In other words, since a current may be generated due to the electro-chemical reaction between remaining hydrogen and air even when supply of the hydrogen and air to the stack is discontinued, an accidental electric shock of a worker may be induced when detaching the output cable from the terminal.
Further, in the process of connecting the fluid supplying tube for supplying fluids to the fuel cells of the stack to the manifold of the stack, the stack is connected to the fluid supplying tube of activating equipment by manually pushing the stack. Accordingly, in the related art, workability may be deteriorated, and air-tightness may not be secured when connecting the fluid supplying tube to the stack manifold since the stack weighing dozens of kilograms is connected to the fluid supplying tube of the activating equipment by manually being pushed.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.